PlaySudoku.us
Expert · Puzzle #900
3
4
7
8
1
2
8
1
1
6
3
9
5
4
2
9
4
7
6
2
3
7
1
For Evil puzzles, study the Y-Wing technique: it chains three cells into a forced elimination.
For Evil puzzles, study the Y-Wing technique: it chains three cells into a forced elimination.
Euler's "problème des 36 officiers" — an unsolvable 6×6 Latin square — is a direct mathematical precursor to Sudoku.
Euler's "problème des 36 officiers" — an unsolvable 6×6 Latin square — is a direct mathematical precursor to Sudoku.